DennisMitchell

Regarding braking, use of engine brake can help a lot. I changed my steering wheel so that I had the paddle shifters. I use them for deceleration. The transmission goes back into D when you get down to a stop. You can also slide over the shifter to manual and take control of the downshifts to use engine braking.

merton

Murray, I'll keep the Alfa comments brief so we don't get booted off here. I loved my GTV-6; hated the $900 upper & lower oil pan (>$1900 in today's $$) and the 30 hours it took me to install it because my mechanic was sick. BTW, I remembered wrong. Mine was an '84.

Anyway, if I can find a TDI with B&O for a price that isn't insane , we'll get it. I'd still appreciate any comments regarding other desirable options that the Prestige has over the Premium Plus. Thanks.

MurrayA4

merton when I chose my Tdi -14 I sat in both with and without B&O put on some Stones and AC/DC and honestly I can't say the upgrade is worthwhile.I went with base system and I'm perfectly happy.Far more important is to have the MMI 3G setup which has the jukebox and Bluetooth audio streaming. couldn't ask for more but that's a very subjective opinion.Even the sub-woofer, an often maligned item, is great when listening to Led Zep.the Who, April Wine (plug for Canadian music) etc.As you can tell I like folk music !

merton

Thanks, Murray. Connectivity is important to me, but I much prefer a direct USB connection over Bluetooth & at least my mind believes I can still hear subtle audio differences. Definitely no MP3's for me. I stream internet radio (alt-country, rock, bluegrass, & folk), so a good interface is important. Sirius/XM sounds like broken glass to me. So the MMI is on the requirement list.

Did the Q5 have an option for magnetic suspension damping? I've enjoyed having that on my 535.

I work on a Nashville-based country music tour. We had shows in Calgary, Saskatoon & Winnipeg last weekend. Brett Kissel is from Alberta & has opened for us on previous tours. He came to see us in Winnipeg. I'm not a huge fan of commercial country music but he does some great stuff. I've seen him perform in a bar on either PEI or Nova Scotia (Sydney?) can't call up old tour dates now- but there is some great music coming out of your country.

Jim

Coolieman1220

Diesels don't engine brake like a gas car. There is no throttle body that stays shut to prevent air from entering the engine like a gas engine. Diesels just keep sucking in air thus, way less engine braking. Too bad we don't have jake brakes!.

DennisMitchell

I thought engine braking has to do with engine compression with little or no detonation of air/fuel mixture.

Coolieman1220

Engine braking is due to throttle vacuum. the closed throttle plate on a gas engine is not allowing the pistons to suck in more air so the vacuum created is what crates the braking resistance felt. On a diesel, since there is no vacuum, it just keeps sucking in air and compressing it. With a jake brake, a valve is mounted on the exhaust which holds the air in the cylinder which creates the braking resistance felt.

This is all done because gas engines rely on air for the engine throttle. diesels rely on fuel.

MurrayA4

Dennis I come down on your side on this one.Diesel downshift "compression" because that's what it is, is produced by the pistons trying to compress air at a high ratio (17:1 on ours.) There is absolutely no doubt that compression braking on a diesel is vastly more effective than on a gasser.
I'm glad by the way, that diesels do in fact produce vacuum.Otherwise my braking foot might get a little tired.Ah well I guess I could always convert to hydroboost ! Sorry can't help myself.

DennisMitchell

I would like to flush this engine braking discussion out some more. I looked up on wikipedia "engine braking". https://en.wikipedia.org/wiki/Engine_braking

The wiki author states much what Coolieman stated in his post. The wiki goes further to state that the diesel engine compression stroke is offset by the decompressing "power" stroke.

But in a diesel engine engine braking scenario, there are other systems that provide "braking". The TDI turbocharger, the EGR, and the DPF.

So I suspect these 3 systems are providing the "engine braking" that I see when take my foot off the accelerator and employ paddle downshifting. Granted, I see much stronger engine braking with my S3 with its gas powered 2.0L and dual clutch transmission downshifts, but the braking with the TDI is very useful.

Coolieman1220

Exactly my point. I'm not saying diesels don't engine brake due to compression. they just don't do as good of a job as a gas engine with a closed throttle body.
It's more work for an engine under vacuum to try and pull air behind a shut throttle body than it is for an engine with a 10:1 or 16:1 compression ratio to compress air.

Air compressed will always want to uncompress. Just looking at the 4 strokes of an engine with no fuel/spark/detonation.
Stroke 1 - Sucking air into the cylinder. Much easier to do in a diesel without a throttle valve. A gas engine will struggle to suck this air in.
Stroke 2 - Compression, the diesel engine will struggle here because the CR is much higher than a gas engine.
Stroke 3 - Detonation - this step does not happen because there is no fuel or spark. Air that is compressed at a higher ratio (diesel) will want to expand more rapidly once uncompressed (think entropy). This pushes the piston back down. Compressed air does have energy.
Stroke 4 - Exhaust valve opens and air leaves. Gas engines make all these crackling popping noises because they are chocked of air. If there is minimal air in, there can't be more air out. This is why diesel engines have exhaust valves (Jake brake) to hold the air in the exhaust. now the exhaust has nowhere to go and creates negative horsepower.

My whole point is that gas engines provide better engine braking than diesels.